Idea...

[patrik]

As you dont have a Grex yet I think you should check out this opportunity .

If you want to get a quick overview of how the caching areas and modes are controlled by the MMU you should look at these sections in the User Manual for respective processor:

For the 68040 (2.5 Pages of reading):
4.3, 4.3.1, 4.3.1.1, 4.3.1.2 and 3.1.3

For the 68060 (3.5 Pages of reading):
5.4, 5.4.1, 5.4.1.1, 5.4.1.2, and 4.1.3

I do recommend reading the 060 User Manual sections first as it is written in a better way... atleast I think so .

I understand your reasons, I just got kind of goo-gaa interested in finding out what levels of performance that can be crammed out of the Grex . As the Grex seems to be able to fully utilize the PCI-bus using non-burst transfers in some configurations I am incredibly curious of how it can perform using burst transfers. There should be some use of burst-transfers btw... when transferring big chunks of data from fastmemory to VRAM (textures for example maybe), burst transfers with MOVE16 should be very sensible.

Though as I said in my earlier post MOVE16 would be crap to measure the raw busspeed performance. Some MMU-tricking,  setting some pages of the VRAM as writethrough cachable and using your method of reading/writing from/to these pages of VRAM should theoretically make it possible to test the raw busspeed performance of the Grex.

If you mean bustest I have used it. Uhm.. was there any point you were coming to regarding this?

The bottom line anyhow is this: I need your expertise for this man!

Have a great day!


/Patrik

[Karlos]

Heh, wasn't a hint, I just mentioned BusTest as an 'already existing' tool for pure bus speed estimations ;-)

I will look into the writethrough cache fudge for register<->VRAM at some point, but I can't really promise to spend much time on it for the forseeable.

If it works, however I have a use for it already ;-)

-edit-

Incidentally, your'e not a GRex owner by any chance are you ? :-) You seem mighty interested in seeing what can be wrung out of it performance wise. An almost unhealthy degree in fact :-D

I'm not particularly concerned about getting one as it isn't developed anymore and hence unsupported, but it definately had the most muscle of the exisiting solutions.

Mediator + SharkPPC (if ever released) would no doubt beat it hands down, however.

[patrik]

No writethrough cache fudge with bustest *sniff* .

Uhm, anyhow... When you try the fudge out, you know someone who will be very interested in the results... and I must admit that I get very curious when you say you already got a use for it but you dont say what!

No, unfortunately I am not a Grex-owner. If I had had a BlizzardPPC for my A1200 though, I can tell you that I wouldnt have hesitated one second to buy one of those for 54EUR from www.ggsdata.se! Today it is unsupported by the manufacturer, but drivers are still developed for it as it is supported by the OpenPCI project. With the speed and expansion possibilities it offers at that price that support would be more than enough for me!

And yes - I am interested to an unhealthy degree in this.. hardware with an edge just makes me so .


/Patrik